JPS6269599A - Placed article inspecting device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to an apparatus for inspecting the arrangement of objects, such as electronic components, mounted on a substrate such as a printed circuit board.

(b) Conventional technology In general, resistors, semiconductor elements, etc. are mounted on printed circuit boards.
The process of mounting various types of chips is automated. However, considering the accuracy of the current automatic mounting, the correct chip is placed in the correct position on the board in the correct posture (position/position).
It is necessary to check whether it is mounted (direction) and whether it has fallen off. Currently, this inspection is performed visually, as it is difficult to automate it.

A method of mechanizing the visual inspection of a printed circuit board assembly using a pattern recognition device, for example, is being considered, but no practical automatic inspection device exists yet.

(c) Problems to be Solved by the Invention The main reasons why it is not possible to realize a practical automatic inspection device even when using a conventional pattern recognition device are as follows. Many of them have only a memory level of 4 degrees) and a clear month bit.

■Image of components mounted on a printed circuit board and the background of the circuit board - is not conditioned for area identification.

That's true.

Conventional character recognition processes information on black figures, characters, etc. drawn on a blank sheet of paper, so if it is binarized with a 1-bit level, it is possible to extract the figure area as is. be.

However, the board on which chip components are mounted is a mixture of chip components and the board surface of various colors, and the image mostly has an intermediate gray level, so the chip area is It was impossible to immediately separate the substrate area (the area outside the area where the chip is mounted).

Therefore, since a detector (TV camera, etc.) cannot obtain a signal indicating whether or not a chip is present in the intended location of the chip component, no matter what program operations are applied in the subsequent information processing process, the chip It was not possible to specify the area of the part, and practical inspection could not be performed.

Furthermore, when AC lighting is adopted in order to inexpensively realize a light source for a pattern recognition device, there is a further problem in that changes in the light star adversely affect measurement accuracy.

In view of the above, the present invention proposes an inspection device that can accurately identify the area of a loaded object such as a chip component from other areas, can detect the loaded object with high accuracy, and can be realized at a low cost. The purpose is to

(d) Means and operation for solving the problems The loaded object inspection apparatus of the present invention includes a base coated with a resist containing a fluorescent material in the area where l/cyst is to be coated, and a support for this base. a filter having fluorescence selectivity, a two-dimensional imaging means for scanning the substrate surface including the loaded object through the filter, and a binarization means for binarizing the obtained image signal; Standard pattern recording means 4a for storing in advance a standard pattern of the loaded object as a reference, the binarized signal, and 4! Comparison means compares the pattern with a quasi-pattern to determine whether the placement state of the loaded object is correct or incorrect.

(E) Examples The present invention will be explained in more detail with reference to Examples below.

FIG. 1 is a diagram showing the configuration of an automatic printed circuit board inspection apparatus in which the present invention is implemented. In the figure, a printed circuit board 1 is held by a chuck mechanism 2, and an X-Y table 3.
− is movably placed on the

A color television camera 5 is provided above the XY table 3 to scan the printed circuit board 1 via a ring illumination device 4. The image captured by the color television camera 5 is separated into three colors: R (red), G (green), and B (blue), and is stored in the image memory 8 via the video signal processing section 6 and A/D converter 7. It is meant to be remembered. The image processing section 9 is a dedicated circuit specially provided for binarization processing, invert processing, and the like. The standard pattern memory 10 includes
A standard pattern when each chip component is arranged on the printed circuit board l is stored.

The mechanical lighting controller 11 also includes a ring lighting device 4.
, the chuck mechanism 2, and the X-Y table 3. These system devices as a whole are CPU1
2.

Next, the operation when scanning a printed circuit board using the printed circuit board automatic inspection device described in -1- will be explained with reference to the flowchart shown in FIG.

First, a reference printed circuit board is set on the X-Y table 3 (step 5TI). Here, the reference printed circuit board is a printed circuit board 3 as shown in FIG.
1 lands 32a, 32b, 33a, 33b, 34a,
34b-1- has not yet been mounted with a chip component. Note that 35 is a wiring pattern. The printed circuit board 31 has lands 32a, 32b, 33a, 33b, 34
A, 34b and a region 36 after the wiring pattern 35 are coated with a resist containing a fluorescent substance (inorganic fluorescent substance: for example, zinc sulfide). In addition, lands 32a and 32b
, 33a, 33b, 34a, 34b and wiring pattern 3
5 has a silvery white color.

This reference printed circuit board 31 is scanned over the entire surface,
Then, the image pattern Ps of the R signal is stored in the image memory 8 (step 5T2). Now, in Figure 3 (line A of al.
Assuming that J- is being scanned, the image signal level is
It changes as shown in FIG. 3(b). Here, the wiring pattern 35, which is the part where the fluorescent material is not applied, is shown.
The silvery white part corresponding to the red wavelength has a high level, and the other areas have a low level because they do not have a bright line spectrum corresponding to the red wavelength because they are coated with a green fluorescent material.

When the reading of the pattern Ps of the reference printed circuit board 3I is completed, the printed circuit board 31' with chip components mounted thereon, which has replaced the reference printed circuit board 31, is subsequently set on the XY table 3 (step 5T3). The printed circuit board 31'' for inspection includes lands 32a, 32b, 33a, 33b,
Chip components 41, 42, and 43 are mounted on 34a and 34b. Chip 41 is brown, chip 42 is white,
Assume that the chip 43 is black. The entire 31° of this printed circuit board for inspection is also scanned, and the target pattern Pc of the R signal of the image is read and latched (
Step 5T4). Now, assuming that the line A in FIG. 4 (al) is being scanned, the image signal level is as shown in FIG.
Changes as shown in . , the part corresponding to the wiring pattern 35, which is also white, and the chip component 41.
The parts corresponding to 42.43 are different at each level, but
The level is higher than that of the green part of the printed circuit board 31'', and the other area, that is, the green part, has a low level because it does not have a bright line spectrum corresponding to the red wavelength.

Subsequently, a difference value between the target pattern Pc and the reference pattern Ps is calculated, and this difference value is stored as the component pattern PO (step 5T5). By this difference value calculation, the same bell components included in the reference pattern Ps and the target pattern Pc are canceled out, so that the wiring pattern portion, the exposed land portion,
Most of the printed circuit board is removed as a level component, and the image of the component pattern PO becomes the one shown in FIG. Now, Figure 5(a)
Assuming that the line A-h is being scanned, the image signal level changes as shown in FIG. Therefore, the level histogram of each window is taken, a predetermined threshold value is set, and the component pattern Po is binarized (step 5T6).

Next, this binary pattern PO and the standard pattern previously stored in the standard pattern memory 10, that is, the binary data pattern when each component is placed in the normal position, are used for each component pattern. compare. Then, the number of bits in which a shift occurs is calculated for each component pattern (step 5T7).

If the obtained binary pattern po of the component of the inspection board is
If all bits of the standard pattern match,
This means that there is no misalignment between the two, which means that the parts are placed and installed correctly.

There is a bit misalignment between the component pattern and the standard pattern.
If the total number of bit deviations exceeds the reference value (step 5T8), it means that the part is placed beyond the limit. Therefore, in this case, processing for placement failure is performed for the printed circuit board (step 5T9).

In step ST8, if the total number of bit deviations is less than the reference value, it is determined whether or not the bit deviation has been checked for all of the printed circuit boards (step 5TIO).
, until the bit misalignment check is completed for all parts.
The processing of steps ST7, ST8, and ST9 is repeated. Bit deviations are checked for all parts, and if the total number of bit deviations for any part is less than or equal to the reference value, processing is performed to indicate that the mounting is satisfactory (step 5T11>).

- When the inspection of the test boards is completed, the process returns to step ST3 and moves to the test of the next test board.

In this embodiment, when the light source is turned on with alternating current pulses as shown in FIG. 6 ta+, the fluorescence is smoothed by the phosphorescence function as shown in FIG. 6 fbl. Therefore, the amount of light does not vary greatly due to AC lighting.

In the embodiment described in (-) above, the total number of bit deviations is used to determine whether the printed circuit board is placed properly, but other methods may be used to determine the quality.

Further, in the above embodiment, a color television camera was used to obtain a two-dimensional scanning signal of the printed circuit board, and its R signal was used, but other B signals etc. may be used, or fluorescence selectivity may be used. Other two-dimensional imaging devices may be used, such as a black and white camera with a filter.

In addition, in the above embodiment, the difference between the reference pattern of the printed circuit board before the object is placed on it and the pattern of the printed circuit board after the object is placed, that is, the target pattern, is taken, and this is used as a binary component pattern. Although we are trying to obtain a converted signal, it is also possible to read only the target pattern and then binarize it. Since a fluorescent material is applied, a binarized pattern of only the parts can be sufficiently obtained without performing a difference calculation.

(f) Effects of the Invention According to the present invention, since a resist containing a fluorescent material is applied to a predetermined area such as an area where parts of a base body are placed, an image can be imaged by scanning in a -dimensional manner. If you get a signal,
Since the level difference between the component area and other areas can be detected on all sides, highly accurate inspection can be performed.

Further, since a resist containing a fluorescent material is applied, the light source can be operated with AC lighting, and a special DC power source is not required, so the device can be realized at low cost.

[Brief explanation of drawings]

Figure 1 is a diagram showing the configuration of an automatic inspection device for printed circuit board J5 in which the present invention is implemented; Figure 2: 1. When inspecting a loaded object of printed circuit board using the automatic inspection device Figure 3 +al is a plan view showing an example of a printed circuit board before parts are loaded onto the device, and Figure 3 (+1) is a diagram showing the same printed circuit board along line A. The image waveform during scanning, Figure 4 (a), shows the image waveform when the device was scanned.
A plan view showing an example of a printed circuit board after mounting components, Figure 4 (hl tri, image waveform when the same printed circuit board is scanned with cotton A, Figure 5 fat L;l, waveform from Figure 4 fbl) An image example of a printed circuit board corresponding to the waveform with the waveform in FIG. 3(b) deleted, FIG. 5 fb) is the same subtracted image waveform, FIG. It is a waveform diagram for explaining the state. ■・31・31′ Niblint board, 2: Chasok mechanism,
3: X-Y table, 5: Color television camera, 8
: image memory, 9: image processing unit, 10: standard pattern memory, 12: CPU. 41, 42, 43: Chisub parts. Patent applicant Tateishi Electric Co., Ltd. Agent
Patent Attorney Shigeru Nakamura Figure 5 Procedures Seal 11 ■Kozuri 2 (Voluntary) May 6, 1986

Claims (1)

[Claims] (1) A loaded object inspection device that inspects the placement state of loaded objects placed in a predetermined area of a base, the base having a resist containing a fluorescent substance applied to the area where the resist is to be applied; a substrate support means for supporting the substrate; a filter having fluorescence selectivity; a two-dimensional imaging means for scanning the surface of the substrate including the loaded object through the filter; and a binary image signal for binarizing the obtained image signal. standard pattern storage means for storing in advance a standard pattern of the loaded object to be compared;
A loaded object inspection device comprising comparison means for comparing the binarized signal with a standard pattern to determine whether the placement state of the loaded object is correct or incorrect.